Depression is a major health problem. Traditional pharmacological treatments have targeted the catecholamine systems with selective reuptake inhibitors, but these have the disadvantages that a) they take extended treatment to achieve efficacy, b) they often require continued dosing, and c) a significant proportion of the clinical population is treatment resistant. The glutamate neurotransmitter system has gained increased attention in the last several years with the advent of the use of the drug ketamine as an antidepressant. Ketamine, which is an antagonist of the NMDA class of glutamate receptors, is advantageous in that it is both rapidly acting and produces persistent effects after a single dose. Animal model studies suggest that ketamine works by producing homeostatic plasticity at glutamate synapses, however the key circuits modified to produce antidepressant actions are not clear. In this proposal we test the hypothesis that NMDA receptors in a region of the brain known as the bed nucleus of the stria terminalis play a key role in the antidepressant actions of ketamine. Moreover, we propose that this occurs via an interaction with the corticotropin receptor factor (CRF) system in this region.